Hollow curved superelastic medical needle and method

ABSTRACT

A needle assembly  10  compromising an infusion needle  11  that includes a needle cannula  13  made of a superelastic material such as Nitinol. The needle cannula is cold-worked or heat annealed to produce a preformed bend  16  that can be straightened within passageway  21  of a coaxial outer cannula  12  for introduction into the body of a patient. Upon deployment from the outer cannula, the needle cannula substantially returns to the preformed configuration for the introduction or extraction of materials at areas lateral to the entry path of the needle assembly. The needle assembly can compromise a plurality of needle cannulae than can be variably arranged or configured for attaining a desired infusion pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is divisional of U.S. patent application Ser. No.12/255,990, filed Oct. 22, 2008, which is a continuation of U.S. patentapplication Ser. No. 11/281/151, filed Nov. 17, 2005 now abandoned,which is a continuation of U.S. patent application Ser. No. 10/678,774,filed Oct. 3, 2003, now abandoned, which is a continuation of U.S.patent application Ser. No. 10/201,112, filed Jul. 22, 2002, nowabandoned, which is a continuation of U.S. patent application Ser. No.09/668,067, filed Sep. 22, 2000, now U.S. Pat. No. 6,425,887 issued Jul.30, 2002, which is a divisional of U.S. patent application Ser. No.09/457,844, filed on Dec. 9, 1999, now U.S. Pat. No. 6,592,559 issuedJul. 15, 2003, which claims the benefit of U.S. Provisional PatentApplication Ser. Nos. 60/111,624, filed Dec. 9, 1998 and 60/130,597filed Apr. 22, 1999, each of which is hereby incorporated herein byreference.

TECHNICAL FIELD

This invention relates generally to medical devices and moreparticularly to needles that are curved for indirect infusion accesswithin the body.

BACKGROUND

Medical procedures involving the vertebrae are typically complicatedbecause of the preciseness required to avoid both neural damage andinjury to major blood vessels, as well as the indirect path that isusually required to access the treatment site.

This is certainly the case when performing a vertebroplasty, a procedurewhereby bone cement, most commonly methyl methacrylate, is injected intoa vertebral body to provide stabilization and/or pain relief in selectedpatients having a spinal condition such as osteolytic metastasis andmyeioma, painful or aggressive hemangiome (benign lesions of the spine),or painful osteoporotic vertebral collapse.

Standard treatment practice depends on the region of the spine beingtreated. For the cervical vertebrae, anterolateral access is used with a15 gauge needle. The large vessels adjacent to the vertebra arelaterally manipulated by the radiologist to provide an access sitebetween the vessels and the pharyngolarynx. An upward access route isrequired because the needle must be introduced below the mandible.

When accessing the thoracic or lumbar vertebrae, typically a large 10gauge needle is used following a transpedicular or posterolateralapproach. The transpedicular route is preferred to avoid spinal nerveinjury and to decrease the probability of the cement leaking intotissues adjacent to the vertebral body.

To obtain complete fill of a damaged vertebral body, it is oftenrequired that a second transpedicular access be made from the oppositeside. A single infusion usually cannot fill the entire target areabecause the needle tip cannot be redirected from the original plane ofentry. Continued infusion of cement from the first access site willusually not result in an adequate infusion due to the tendency of thematerial to set before it fills all of the affected area, therebybecoming a baffle to itself. Furthermore, the thick density of themarrow and structures, such as veins, usually acts to impede free flowof the cement within the vertebral body.

Another concern during the procedure is accidental puncture of the theseveins. Because vertebral veins lead directly to the lungs, there is asignificant risk of pulmonary embolism if cement is accidentallyintroduced therein.

The inability to adequately maneuver the needle cannula tip within abody or around structures is a major limitation of the straight needle.Additional needle sticks to complete a medical procedure result indiscomfort to the patient and additional risk of leakage and othercomplications.

To sufficiently access a vertebral body for complete infusion of cement,the needle tip must be capable of being deflected at significantly largeangles from the original axis. This would require that the needle have adistal bend so that the needle could be rotated to selectively directthe material.

Rigid curved needles are well known for suturing applications; however,adding anything more than a slight bend to an infusion needle limits itsaccess path and ability to deeply penetrate tissue, especially bone. Forexample, a rigid curved needle is unsuitable for use in a vertebroplastyprocedure where the needle cannula must be driven through the bone anddeep into the vertebral body using a relatively straight approach andmaintained in place to avoid additional damage to the entry site. Whilethe initial needle access must be done with a straight needle ofsufficient strength to penetrate bone, the ideal approach would be todirect a lateral infusion of cement following needle penetration, andthen to withdraw the needle along its original path.

Accomplishing this is problematic. The tissue density and resistance ofthe tissue to penetration at the treatment site can require that theinner infusion member be nearly as stiff as the outer piercing cannula.A certain degree of needle rigidity is required in order to be able tomaneuver the needle and accurately direct flow of material.

While stainless steel needles having a slight distal bend are known, theamount of needle curvature necessary to provide adequate lateralinfusion is not possible—the needle plasticly deforms once inside theouter restraining cannula and hence is unable to return resiliently toits preformed shape. Thus, a second needle access would still berequired to provide adequate filling.

Other medical procedures present similar problems when a single straightneedle is used. One example is tumor ablation where percutaneous ethanolinjection is used to treat carcinoma of the liver and kidney. Originallyintroduced as a palliative treatment for inoperable hepatocellularcarcinoma of the liver, ethanol injection has now been shown to havecurative potential comparable to resection in many patients, especiallyfor smaller tumors.

Practice has been to inject ethanol directly into masses using astraight needle and to allow the ethanol to infuse from one or more sideholes into the tissue. The problem is that the infusion may notpenetrate any deeper than the needle tract; thus portions of the tumorare not effectively treated. It is desirable to provide a device formore effective infusion of ethanol into the tumor mass.

SUMMARY OF THE INVENTION

The foregoing problems are solved and a technical advance is achieved inan infusion needle made of rigid superelastic material and having atleast one performed bend along the distal portion of its length. Theneedle is used as an inner cannula coaxially with a second hollowcannula for restraining the inner needle cannula in a substantiallystraight orientation during percutaneous introduction to the targetsite, whereby the inner needle cannula is deployed to resiliently returnto its preformed configuration.

The ability of the preformed inner needle cannula to deflect laterallyupon exiting the outer cannula allows the inner needle cannula to infuseor aspirate material at multiple points within different planes in thebody as the inner infusion needle rotates about its longitudinal axis.This helps to reduce or eliminate the need for additional “sticks” withthe outer cannula; it also allows the operator to make an entry from onedirection, then to deploy the curved inner cannula to reach a site thatcannot be accessed directly, such as where another structure lies alongthe access path, thereby blocking the target site.

The preferred material for the inner cannula is a superelastic, shapememory alloy such as sold under the trademark Nitinol (Ni—Ti); however,there are other non Ni Ti alloys that may be used. A Nitinol alloy isdesirably selected that has properties whereby the temperature at whichthe martensitic to austenitic phase change occurs is lower than theworking temperature of the device (i.e. room temperature).

As described in U.S. Pat. No. 5,597,378, incorporated herein byreference, a permanent bend may be heat set in a superelastic Nitinolcannula by maintaining the cannula in the desired final shape whilesubjecting it to a prescribed high temperature for a specific timeperiod. The resulting cannula can be elastically manipulated far beyondthe point at which stainless steel or other metals would experienceplastic deformation. Nitinol and other superelastic materials whensufficiently deformed undergo a local phase change at the point ofstress to what is called “stress-induced martensite” (SIM). When thestress is released, the material resiliently returns to the austeniticstate.

A second method of imparting a permanent bend to the needle material isby a process commonly known as “cold working.” Cold working involvesmechanically overstressing or overbending the superelastic cannula. Thematerial within the bending region undergoes a localized phase shiftfrom austenite to martensite and does not fully return to its originalshape. In the case of the cold-worked cannula, the result is a permanentcurve about the bending zone which has been locked in to at least apartial martensitic crystalline state.

In contrast, when heat treating is used, the entire heat-annealedcannula is in a austenitic condition, even in the curved region, and isonly temporarily transformed to martensite under sufficient bendingstresses. Therefore, the flexural properties of the annealed cannulavary little across its length.

Conversely, the bend of a cold-worked cannula, which containsmartensite, has increased resistance to deformation and therefore holdsits shape better than the more flexible bend of the pure austeniticcannula This increased rigidity can be an advantage for certain clinicalapplications.

In one aspect of the invention, an introducer trocar or stylet is usedwith either the outer or inner needle cannula, depending on the luminatesize of the needle, to facilitate access to tissue and/or prevent coringtissue into the distal tip of the needle device. The infusion needle orinner cannula is introduced through the outer cannula after access hasbeen established and the trocar or stylet is removed.

Depending on the size of the cannulas, the degree of the preformed bend,or the method used to form the bend, the inner cannula or needle mayslightly deform the outer cannula as the preformed bend present in theinner needle or cannula is constrained within the outer cannula. As aresult, the outer cannula may be deflected a few degrees from its normallongitudinal axis at a point corresponding to the bend of the innercannula. As the inner cannula is deployed from the outer cannula, theinner cannula deflects laterally until the entire region of the bend isunsheathed. The distal opening of the inner cannula is oriented at alarge angle (preferably within the range of)60-90° from the originallongitudinal axis when the inner needle is fully deployed.

The ability of the inner cannula to deflect at a significant angle fromthe original longitudinal axis has great utility in a number ofapplications where straight access is required followed by redirectionof the distal opening. This deflection permits access to a differentsite without the necessity of withdrawing and reintroducing the needle.

A primary example of such a procedure is vertebroplasty in whichinfusion of the stabilizing cement with a straight needle often requiresa second stick to provide complete filling to stabilize the vertebralbody while avoiding damage to delicate structures such as veins. As withthe standard single-needle procedure involving the thoracic or lumbarregions of the spine, a transpedicular approach is normally used wherebythe larger outer needle cannula, such as a coaxial Jamshldi-type needle,is introduced into the damaged or diseased vertebral body. The outerneedle includes an inner introducer trocar which is then replaced with ainner curved needle for infusion of the cement.

The ability of the curved needle to deflect laterally and rotate toreach multiple planes gives it a significant advantages over straightneedles which have a limited range of movement. Because of thisadditional range of movement, the curved needle can usually complete thevertebroplasty procedure with a single access of the vertebral body.This avoids additional discomfort and risks to the patient, whichinclude complications from leakage of cement or inadvertent infusioninto non-target areas.

In addition to using the coaxial needle for infusion of cement as above,the device can also be adapted for aspirating material or serving as aconduit for the introduction of other devices. The apparatus may be usedfor a percutaneous corpectomy, a procedure which involves fusion anddecompression of two or more vertebrae by first aspirating tissue fromthe damaged vertebral bodies, then introducing a prosthesis having acarbon fiber composite cage packed with bone graft material to serve asscaffolding for the affected vertebrae. Once the cage is properlypositioned, methyl methacrylate or another suitable material is infusedinto the vertebral bodies to secure the prosthesis. The percutaneouscorpectamy offers less trauma, and with the reinforcement cage, providessuperior rigidity over a conventional corpectomy utilizing bone graftmaterial alone.

In another aspect of the invention, the coaxial needle can be adaptedfor paraspinal use to inject medicaments within the neural canal orepidural space as part of management and/or diagnosis of pain.Preferably, the outer cannula has a tip adapted for piercing softtissue. This outer needle cannula, preferably about twenty-one (21)gauge, is introduced percutaneously parallel to the spinal column alongwith an internal stylet with matched bevel to prevent coring tissue intothe distal opening. The stylet is removed and the curved needle, abouttwenty-five (25) gauge, is inserted into the outer cannula. The needleassembly is then maneuvered to contact a nerve root during a diagnosticprocedure to help recreate pain symptoms of the patient. The innerinfusion needle also includes a stylet which is situated within thepassageway of the needle as it is directed to the target site. Thestylet is then removed from the infusion needle and medicaments,commonly steroids such as celestone (injected with lidocaine), kenalog,or methylprednisone are introduced to the treatment site. The innerneedle is then withdrawn into the outer sheathing cannula and both arewithdrawn from the patient.

Another use of the smaller gauge paraspinal needle is for diskographywhich consists of injecting a contrast agent (preferably nonioniccontrast media) directly into the patient's disk to delineate the extentof any malformation or injury to the vertebral body.

Yet another aspect of the invention solves the problem of infusion ofethanol into a tumor mass by utilizing a plurality of curved needlecannulae deployed within an cannula introduced into the tumor where thecurved needle cannulae radiate outward into an umbrella-shapedconfiguration. Infusion can take place at multiple points within thetumor to provide wider dispersion of the ethanol. Following treatment,the curved needle cannulae are withdrawn into the cannula and the deviceis removed from the patient.

In a related aspect, one or more needle cannulae are located proximal tothe distal end of the infusion needle. These proximally-located cannulaeallow infusion of medicaments at different points along the length ofthe device. By having multiple sets of needles arranged in the umbrellaconfiguration, the volume of tissue treated is increased. The coaxialouter cannula includes a plurality of side apertures that allow theproximally-located needle cannulae to deploy after the infusion needleis placed at the desired location in the body and the outer cannula iswithdrawn. An outer sheath over the coaxial outer cannula selectivelyexposes the side apertures to permit the appropriate alignment of needlecannulae and apertures when there are multiple rows of each.

The invention has applicability in any clinical situation where astraight approach is dictated and there is a need to avoid anobstructing structure (a large vessel, bowel loop, etc.) in the entrypath, or the need to redirect the approach to a more lateral pathway toinfuse medicaments or aspirate, such as to drain an abscess.

In addition to infusion or aspiration, the invention can provide aconduit for introducing and/or directing the path of other medicaldevices within the body such as radio-frequency ablation catheters orwire guides. This would allow a straight approach to a critical juncturewhereafter the curved infusion needle can be deployed to preciselyproceed to the desired anatomical site, especially in situations such asa luminal bifurcation or when access to an ostium is required.

Another use of the invention is to place the infusion needle in abronchoscope or colonoscope which can serve as the outer constrainingdevice. Under visualization, the inner needle then can be directed toperform a biopsy or other type of procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an illustrative embodiment of the curvedneedle inner cannula;

FIG. 2 is a top view of an outer needle cannula with an introducertrocar and the inner curved needle cannula;

FIG. 3 is a top view of the assembly of the inner curved needle cannulainside the outer needle cannula;

FIG. 4 is an exploded isometric view of a second embodiment of the innerand outer cannula;

FIG. 5 depicts a pictorial view of the inner cannula of FIG. 4 with anintroducer stylet;

FIG. 6 is a side view of the inner cannula of FIG. 4 being initiallydeployed from the outer cannula;

FIG. 7 is a side view of the inner cannula of FIG. 4 being furtherdeployed from the outer cannula;

FIG. 8 is a side view of the inner cannula of FIG. 4 being still furtherdeployed from the outer cannula;

FIG. 9 is a partially sectional view depicting the apparatus of FIG. 2being introduced into a vertebral body;

FIG. 10 is a partially sectional view similar to FIG. 9, depicting ofthe apparatus of FIG. 2 infusing cement into a vertebral body.

FIG. 11 is a broken, partially sectioned view similar to FIGS. 9 and 10,depicting of the apparatus of FIG. 2 infusing additional cement into avertebral body.

FIG. 12 is an isometric view of a third embodiment of the apparatus;

FIG. 13 is a side view of the multi-directional infusion needleillustrated in of FIG. 12;

FIG. 14 is a broken, side view of the needle of FIG. 13 partiallyshowing the needle deployed;

FIG. 15 is a side view of a trocar introducer used with the embodimentof FIG. 12;

FIG. 16 is a side view of the proximal assembly portion of the apparatusillustrated in FIG. 12;

FIG. 17 is a side view of a fourth embodiment of the apparatus;

FIG. 18 is a broken, partially-sectioned side view of the apparatusillustrated in FIG. 17 prior to deployment;

FIG. 19 is a transverse cross-sectional view of coaxial outer cannuladepicted in FIG. 17;

FIG. 20 depicts cross-sectional views of two embodiments of coaxialouter cannula depicted in FIG. 17;

FIG. 21 is an isometric view of a fifth embodiment of the presentapparatus; and

FIG. 22 is an isometric view similar to that of FIG. 21 showing theapparatus fully deployed.

DETAILED DESCRIPTION

FIG. 1 depicts a needle assembly 10 comprising an infusion needle 11with a preformed bend 16 for lateral infusion or aspiration ofmedicaments and other materials. As defined herein, the “needle assembly10” can comprise infusion needle 11 alone or infusion needle 11 incombination with other components. The “infusion needle 11” as definedherein comprises one or more needle cannulae having a preformed bend 16.

The infusion needle 11 of FIG. 1 is comprised of a superelastic alloyneedle cannula 13, preferably the alloy sold under the trademarkNitinol, that is soldered or otherwise affixed to a well-known needlehub 14 using one of a selected number of well-known techniques,including that of Hall described in U.S. Pat. No. 5,354,623 whosedisclosure is expressly incorporated herein by reference, and a flange23 which has a first tapered or pointed end 24 whose shape is readilydistinguishable from the second, squared end 42.

First end 24 corresponds to the direction of preformed bend 16 in needlecannula 13 of infusion needle 11. Bend 16 is formed in the Nitinolneedle cannula 13 by either the well-known process of deforming thecannula under extreme heat for a prescribed period of time, whichproduces a cannula entirely in the austenitic state, or by cold workingthe cannula, which involves applying a large amount of mechanical stressto deflect the 15 cannula well beyond the desired amount of permanentbend. Cold working permanently locks a crystalline structure in thebending zone into at least a partial martensitic condition while theunstressed portions of the cannula remain in the austenitic state.

Cold worked Ni—Ti alloys are discussed in “Linear Superelasticity InCold-Worked Ni—Ti”, (Zadno and Duerig) pp. 414 to 419, in EngineeringAspects of Shape Memory Alloys, Butterworth-Heineman, Boston, Mass.(Duerig et al, editors) which is incorporated herein by reference. Inaddition to Nitinol, superelastic or pseudoelastic copper alloys, suchas Cu—Al—Ni, Cu—Al—Zi, and Cu—Zi, are available as alternative needlecannula materials. Flexible polymeric materials with sufficient rigidityfor both deployment and shape memory to assume a desired curve may alsobe used in certain applications, either alone or in combination withreinforcing metal components such as a metal braid or tip.

Preformed bend 16 of infusion needle 11 forms a distal portion of needlecannula 13, preferably close to about 25% of the length of needlecannula 13 in the embodiment shown in FIG. 1. The large size of theinfusion needle, preferably 10 to 18 gauge, makes this particularembodiment suitable for penetrating a vertebral body to perform avertebroplasty or percutaneous corpectomy procedure. A more preferredrange is 12 to 17 gauge, with the most preferred cannula size being 13to 15 gauge.

With regard to a vertebroplasty and corpectomy procedures, the largergauge cannula has both the strength to penetrate dense bone material aswell as a sufficient lumen diameter to aspirate material from thevertebral body and to infuse highly viscous bone cement, such as methylmethacrylate. The preferred preformed bend 16 of the infusion needle 11has a constant radius. For the embodiment of FIG. 1, the preferredradius of distal bend 16 is approximately 3.0 cm for a 13 gauge needle,and approximately 2.5 cm for a 14 gauge needle. Although theillustrative embodiment has a constant bend radius, an increasing ordecreasing radius bend could be employed for certain clinicalapplications. Furthermore, it is possible to introduce more than onebend into the superelastic cannula for applications requiring a specialneedle configuration.

The primary purpose of using a Nitinol or other superelastic alloycannula is that the cannula can be constrained into one shape duringpassage to the treatment site, then deployed into the preformedconfiguration without experiencing any plastic deformation.

FIG. 2 depicts a pair of needles to be used coaxially in that manner,including the infusion needle 11 of FIG. 1 and a coaxial outer cannula12 for maintaining inner infusion needle 11 in a substantially straightconfiguration while being introduced to the treatment site. Theembodiment depicted in FIG. 2 is Jamshidi-type needle (Manan Inc.,Northbrook, Ill.) which is a two-part needle assembly 43, and is mostcommonly used for accessing dense, hard tissue such as bone, fibrousmaterial, etc. Thus, it is well suited for penetrating the wall of avertebral body wherein the infusion needle 11 can be deployed.

The two-part needle assembly 43 includes a coaxial outer cannula 12having a stainless steel cannula 19 with an inner passageway 21 that issufficiently large to accommodate inner infusion needle 11. For example,the standard 11 gauge Jamshidi-type needle suitable for accessing avertebral body would be used with thirteen (13) gauge inner curvedneedle. Stainless steel cannula 19 is affixed proximally to a handle 26and a connector hub 31 (shown in FIG. 3). The connector hub 31 receivesthe second part of the two-part needle assembly 43, the coaxial outercannula introducer 52 which preferably comprises a trocar 25. The trocarhub 27 locks into handle 26 of coaxial outer cannula 12. The beveled tip30 of trocar 25 extends approximately 5 mm beyond the distal tip 22 ofcoaxial outer cannula 12 and assists in penetration. Trocar 25 alsoserves to prevent the coaxial outer cannula 12 from coring a sample ofbone or other material during access.

After outer needle assembly 43 has been directed to the target site,trocar 25 is removed from coaxial outer cannula 12 and infusion needle11 is inserted into passageway 21 of the coaxial outer cannula 12, asshown in FIG. 3. To maintain openness of the infusion needle passageway15 and to prevent tissue coring during deployment, an inner needleintroducer stylet 46 can be introduced coaxially inside the infusionneedle. Inner needle introducer stylet 45 includes a handle 83 and ashaft 46 which is made of a flexible, high-tensile. polymeric materialsuch as polyetherethylketone (PEEK) to allow stylet 45 to assume thecontour of preformed bend 16 after deployment.

Inner infusion needle 11 straightens as it is loaded into coaxial outercannula 12. As the portion including preformed bend 16 of infusionneedle 11 extends out from tip 22 of coaxial outer cannula 12 asdepicted in FIG. 3, infusion needle 11 assumes the preformed shape dueto the superelastic properties of needle cannula 13. For infusion, innerneedle introducer stylet 52, which helps prevent coring of tissue intopassageway 21 of coaxial outer cannula 12, is removed. The tapered or“arrow” end 24 of flange 23 of proximal hub 14 corresponds with thedeflection plane 29 of infusion needle 11.

By maneuvering flange 28, the inner curved needle 13 can be rotated ineither direction 28 to reorient the plane of deflection 29 and place thetip opening 17 at multiple locations within the area being treated.

In FIG. 3, tip 17 is deflected at an angle 44 of approximately 60° to70° from the device longitudinal axis 18. This gives, for example, witha thirteen (13) gauge infusion needle 11, a lateral reach, measured fromtip 17 to longitudinal axis 18, of nearly thirty (30) millimeters in anydirection.

While the degree of deflection required is determined by the applicationand desired lateral reach of the device, it is also limited by the sizeof the cannula if the permanent bend is cold worked into the material.Cold working provides a stiffer bend which can be advantageous incertain applications such as vertebroplasty and biopsy of dense tissue;it is more difficult to permanently deform a larger gauge Nitinolcannula without application of extreme heat. For the embodimentscontemplated, the angle of deflection 44 can encompass a range of 30° to110°, with a preferred range of 40 to 90° for most applications.

FIG. 4 depicts a second version of the inner curved needle and sheathingouter needle adapted for use in the injection of medicaments, contrastmedia, or other non-viscous agents. The infusion needle 11 is comprisedof a smaller gauge needle cannula 13, preferably around twenty-five (25)gauge, mounted to a proximal hub 14. The preformed bend 16 of individualneedle cannula 13 has a slightly tighter radius than that illustrated inFIGS. 1 through 3.

Still referring to FIG. 4, the coaxial outer cannula 12 includes acorrespondingly sized needle cannula 19, preferably around twenty-one(21) gauge, attached to a standard needle hub that is adapted to receiveproximal hub 14 of infusion needle 11. The embodiment of FIG. 4 is usedwith a plurality of stylets that are inserted within both the inner andouter needles during their respective introduction into the body. Thefirst is an outer cannula introducer stylet 52 that is inserted into thepassageway 21 of coaxial outer cannula 12. The coaxial outer cannula 12and outer cannula introducer stylet 52 are inserted together into thepatient. The stylet, which is preferably a stainless steel stylet wire46 with an attached standard plastic needle hub 47, prevents the coaxialouter cannula 12 from coring tissue into passageway 21 at distal tip 22.

Once coaxial outer cannula 12 is in position, outer cannula introducerstylet 52 is withdrawn from coaxial outer cannula 12 and infusion needle11 and second introducer stylet 45 are inserted together into outerneedle passageway 21. The inner needle introducer stylet 45, which islonger than outer cannula introducer stylet 52 in order to fit thelonger infusion needle 11, serves a similar function to the outercannula introducer stylet 52 by preventing coring of tissue wheninfusion needle 11 is deployed from coaxial outer cannula 12.

As illustrated in FIGS. 4 and 5, proximal hub 14 of infusion needle 11is adapted such that hub 53 of inner needle introducer stylet 45 lockstogether with proximal hub 14 to keep the two in alignment. This lockingmechanism includes a molded protuberance 49 on hub 53 that fits within arecess 50 on proximal hub 14. The purpose of maintaining alignment ofhub 53 and proximal hub 14 is to match the beveled surface 51 at the tipof the inner needle introducer stylet 45, shown in FIG. 5, with thebeveled edge at the tip 17 of infusion needle 11.

FIGS. 6 through 8 depict the deployment of infusion needle 11 fromwithin outer needle cannula 12. FIG. 6 shows infusion needle 11 duringinitial deployment from coaxial outer cannula 12. The preformed bend 16of the infusion needle 11 is constrained by the cannula 19; however, asillustrated in FIG. 6, preformed bend 16 may be of sufficient stiffnessto slightly deform outer cannula 19 while infusion needle 11 is insidecoaxial outer cannula 12. Despite this slight deformation, coaxial outercannula 12 is still substantially straight.

As depicted in FIG. 7, stress preformed bend 16 places on outer cannula19 relaxes as infusion needle 11 is further deployed and the angle ofdeflection 44 (measured from longitudinal axis 18 of coaxial outercannula 12 to the opening at tip 17 of infusion needle 11) is increased.As infusion needle 11 is further deployed as depicted in FIG. 8, fullyexposing preformed bend 16 to produce the largest angle of deflection44, the unstressed outer cannula returns to a straight configuration.

The phenomenon depicted in FIGS. 6 through 8 is most noticeable whenusing smaller gauge cannulae, such as shown in FIGS. 4 and 5. The largergauge outer cannula of FIGS. 1 to 3 is more resistant to deformationthan that of FIGS. 4 and 5. Naturally, the tendency of the stressedouter cannula to deform is also very much dependent on the stiffness andradius of the preformed bend 16 as well as the thickness of the cannulawall and material used. To eliminate this deformation duringintroduction of the device into the body, stylet 45, as depicted in FIG.5, can be used as a stiffener until removed immediately before theportion having preformed bend 16 is deployed.

FIGS. 9 through 11 depict the use of the device illustrated in FIG. 3 toperform a vertebroplasty procedure on a pathological vertebral body 33using a transpedicular approach. As depicted in FIG. 9, coaxial outercannula 12 with introducer trocar 25 is introduced through the wall 38and into the marrow 37 of the vertebral body 33. The transpedicularroute of access places the needle between the mammillary process 34 andaccessory process 35 of the vertebral arch 55. The vertebral arch 55 isattached posteriorly to the vertebral body 33 and together they comprisethe vertebra 54 and form the walls of the vertebral foremen 36.

Once coaxial outer cannula 12 and inner introducer trocar 25 are withinthe internal region or marrow 37 of the vertebral body, trocar 25 iswithdrawn from the coaxial outer cannula 12 and infusion needle 11 isinserted in its place. FIG. 10 depicts infusion needle 11 infusing bonecement 41, commonly methyl methacrylate, into vertebral body 33 toprovide it with improved structural integrity. As depicted in FIG. 11,infusion needle 11 can be partially withdrawn or rotated to obtain morecomplete filling or to avoid the network of vertebral veins. Even thoughthe vertebral body may not need to be completely filled, the density ofmarrow 37 would still necessitate a second transpedicular stick in theabsence of the instant apparatus infusing cement within multiple planeswithin vertebral body 33. Upon completion of the procedure, infusionneedle 11 is withdrawn back into coaxial outer cannula 12 and both areremoved from vertebral body 33.

The utility of the hollow, curved superelastic needles is certainly notlimited to procedures involving the spine. Such needles are useful atmany sites within the body that might require straight access by aneedle, followed by indirect or lateral infusion, aspiration, orsampling. For example, the inner needle could be adapted to take biopsysamples from dense tissue, such as a breast lesion, especially whereindirect access is might be desirable.

FIG. 12 is an isometric view of hollow, curved superelastic needles inwhich needle assembly 10 comprises a multiple needle assembly 70 usefulin infusion of ethanol or other medicaments into a tumor. In FIG. 12,needle assembly 10 comprises an infusion needle 11, which includes amultiple needle assembly 70 comprising a plurality of needle cannulae13, each having a preformed bend 16, a proximal assembly 58 forconstraining the multiple needle assembly 70, and a coaxial outercannula 12 for introducing the multiple needle assembly 70 to itsanatomical target.

The multiple needle assembly 70 in FIG. 13 includes a base cannula 56affixed to a proximal hub 14 such as a standard female luer fitting. Aplurality of needle cannulae 13 are manifolded into base cannula 56,preferably evenly spaced in an umbrella configuration 75, and affixed inplace with a solder joint 57. In the structure illustrated in FIG. 12,five needle cannulae 13 are used; from two to as many as appropriate forthe given cannula size can be used. As with the other versions, needlecannulae 13 are preferably made of Nitinol that is either annealed orcold-worked to produce the preformed bend 16. In the structureillustrated in FIG. 12, the coaxial outer cannula 12 has an outerdiameter of approximately 0.072 inches and an inner diameter of around0.06 inches, while the individual curved needle cannulae 13 have anouter diameter of 0.02 inches and an inner diameter of about 0.12inches. As shown in FIG. 14, the tips 17 of the needle cannulae 13 maybe beveled to better penetrate tissue.

Deployment of curved needle cannulae 13 of multiple needle assembly 70is depicted in FIG. 14. Needle cannulae 13 are restrained by coaxialouter cannula 12 until multiple needle assembly 70 is advanced, exposingthe distal end portions of needle cannulae 13 at distal end 22 ofcoaxial outer cannula 12, whereby they radiate outward to assume, whenfully advanced, the umbrella configuration 75 shown in FIG. 13.

FIG. 15 depicts a side view of an outer needle assembly comprising acoaxial outer cannula 12 and outer cannula introducer stylet 52 used inplacement of the multiple needle assembly 70 of FIGS. 12 through 14. Theouter cannula introducer stylet 52 is inserted into passageway 21 ofcoaxial outer cannula 12 with the male proximal hub 47 of the outercannula introducer stylet 52 fitting into the female proximal hub 20 ofcoaxial outer cannula 12 when the outer cannula introducer stylet 52 isfully advanced. Outer cannula introducer stylet 52 includes a sharp tip63, such as the diamond-shape tip depicted, for penetrating tissue.

The outer cannula introducer stylet 52 and coaxial outer cannula 12 maybe introduced percutaneously into the liver or kidney and placed at thedesired treatment location. The outer cannula introducer stylet 52 isthen removed. The proximal assembly 58 with the preloaded multipleneedle assembly is then advanced into the coaxial outer cannula 12 whichremains in the patient. In the version illustrated in FIGS. 12 through15, the coaxial outer cannula preferably has an outer diameter of about0.095 inches and an inner diameter of about 0.076 inches, while theouter diameter of the inner stylet is preferably about 0.068 inches.

FIG. 16 a side view of the proximal assembly 58 shown of FIG. 12. TheProximal assembly 58 includes a distal male adaptor 60 connected to anintermediate cannula 59 that is sufficiently large to accommodatemultiple needle assembly 70. At the proximal end of the intermediatecannula 59 is proximal assembly female adaptor 61 which is connectedproximally to a proximal assembly hub 62, such as a Tuohy-Borst adaptor.Proximal assembly hub 62 is utilized by the physician duringmanipulation of the device.

The multiple needle assembly 70 of FIG. 13 is loaded into lumen 64 atthe proximal end 65 of the proximal assembly hub 62, with the needlecannulae 13 remaining within intermediate cannula 59. Distal end 66 ofproximal assembly 58 with preloaded multiple needle assembly 70 is theninserted into proximal hub 20 of the coaxial outer cannula as depictedin FIG. 12. The multiple needle assembly 70 is then advanced from theproximal assembly 58 into the coaxial outer cannula 12 where it isdeployed as depicted in FIGS. 12 to 14. Ethanol is infused into multipleneedle assembly 70 via the proximal hub 14 of the infusion needle 11.Following treatment, the multiple needle assembly 70 is withdrawn intocoaxial outer cannula 12 and the entire needle assembly 10 is removedfrom the patient.

FIGS. 21 and 22 depict a variation of needle assembly 10 of FIG. 12 inwhich infusion needle 11 and coaxial outer cannula 12 are connected to acoaxial handle 76 used to advance and deploy multiple needle assembly 70releasably from constraint of coaxial outer cannula 12. As shown,coaxial handle 76 comprises a stationary outer component 77 that fitsover base cannula 56 of multiple needle assembly 70 and attaches toproximal hub 20. A slidable inner component 78 further comprises a thumbpiece 79 used by the physician to advance or retract the coaxial outercannula 12 as the slidable inner component 78 retracts into stationaryouter component 77.

In FIG. 21, the needle assembly is depicted in the introducer positionwith the thumb piece 79 advanced fully forward within a slot 80 in outerslidable component 77.

FIG. 22 depicts the deployment state of needle assembly 10 in whichthumb piece 79 has been moved to the most proximal position within slot80. In this position, coaxial outer cannula 12 is retracted to fullyexpose the plurality of needle cannulae 13 which can assume theirunconstrained configuration with the preformed bends 16.

This type of handle can be used with both the multiple and singleinfusion needle where a introducer trocar or stylet is not required.Other well-known types of coaxial handles 76 include, but are notlimited to, screw-type, ratchet-type, or trigger-activated handles whichallow coaxial outer cannula 12 to be longitudinally displaced relativeto infusion needle 11. To reduce the need for a trocar or stylet forfacilitating tissue penetration, distal tip 22 of coaxial outer cannula12 can be shaped into a needle point such as depicted, or into anon-coring point to help maintain an open outer cannula passageway 21.

A syringe or other reservoir container can be attached to proximal hub14 as an infusate source or for collection of aspirated material. Inaddition, a reservoir, such as a syringe, can be incorporated internallywithin coaxial handle 76 of needle assembly 10 or integrally attachedthereto.

Another version of multiple needle assembly 70 is depicted in FIGS.17-20 whereby there are one or more groupings of proximally-locatedneedles 73 in addition to the distally-located needles 74 that aresimilar to those illustrated in of FIG. 12. By locating the additionalneedle cannulae 13 proximal to those at the distal end, wider dispersaland coverage is attained for infusion of medicaments.

In the version illustrated in FIG. 17, there is an arrangement of fourneedle cannulae comprising the distally-located needles 74, while atleast one other group comprising proximally-located needles 73 locatedalong the length of infusion needle 11 provides for simultaneousinfusion in a more proximal location. The needle cannulae 13 of theproximally-located and distally-located needles 73, 74 can vary inconfiguration, length, number, and how they are attached to a basecannula 56 such as that shown in FIG. 13. For example, individual needlecannulae 13 within an umbrella configuration 75 or betweenproximally-located and distally-located needles 73, 74 can be longer, orhave a different radius than others, to vary the distribution pattern ofthe infusate.

As depicted in FIGS. 17 and 18, each pair of oppositely-disposed needlecannulae 13 within a grouping of four proximally-located needles 73 arelongitudinally offset with respect to the adjacent pair located ninetydegrees (90°) therefrom, as are the side apertures 67 from which theyemerge. With regard to attachment, possibilities include, but are notlimited to, having all needle cannulae 13 attaching to a single basecannula 56; dividing base cannula 56 such that a separate portionextends distally from the proximally-located needles 73 to join thedistally-located needles 74, or eliminating the base cannula 56 suchthat needle cannulae 13 of multiple needle assembly 70 are separate andrun the length of infusion needle 11.

To constrain needle cannulae 13 for introduction along a single pathwayinto the body, a coaxial outer cannula 12 is used that has sideapertures 67 in the cannula to permit the proximally-located needles 73to deploy outward therethrough for lateral infusion. FIG. 18 shows asectioned view of the needle assembly of FIG. 17 in which the needlecannulae 13 are constrained in the introduction position. An introducercannula 68 is used to selectively expose side apertures 67 in versionswhere the arrangement of needles is such that individual needle cannulae13 may prematurely exit a non-designated hole or row, preventing ordelaying proper deployment of the multiple needle assembly 70. Bymaintaining the introducer sheath over side apertures 67 untildistally-located needles 73 are deployed, proper deployment of allneedle cannulae 13 is easier.

FIGS. 19 and 20 illustrate intraluminal guides 69 to help facilitateproper alignment of needle cannulae 13 with a designated side aperture67. In FIG. 19, a series of ridges 71 within passageway 21 of coaxialouter cannula 12 guide the needle cannulae 13 to align with a designatedside aperture 67. FIG. 20 depicts an alternative intraluminal guide 69in which the needle cannulae 13 travel longitudinally within grooves 72formed in the inner wall of passageway 21.

1. A needle assembly, comprising: a plurality of needle cannulae eachhaving a passageway and a distal tip portion, each said needle cannula,while in its unconstrained configuration, having at least one preformedbend proximate to said distal tip portion and being constrainable to asecond configuration, whereby at release of external constrainingforces, said distal tip portion of each said needle cannulasubstantially returns to the unconstrained configuration extendingforwardly and radially outwardly from a respective said preformed bend;wherein said needle cannulae comprise a superelastic Ni—Ti alloy; andwherein the at least one preformed bend of each needle cannula of saidplurality of needle cannulae is induced by mechanical deformation of theneedle cannula such that the superelastic material of the at least onepreformed bend includes a martensitic crystalline structure, whilenon-mechanically defomied portions of the needle cannula comprise asubstantially austenitic crystalline structure.
 2. The needle assemblyof claim 1, also comprising a straight coaxial outer cannula for receiptof said plurality of needle cannulae.
 3. The needle assembly of claim 2,wherein said coaxial outer cannula has an end opening arranged forpassage of said plurality of needle cannulae out of said outer cannula.4. The needle assembly of claim 2, wherein said plurality of needlecannulae are received together in a single lumen of said coaxial outercannula.
 5. The needle assembly of claim 2, wherein said coaxial outercannula has a plurality of side holes, each of said side holes arrangedfor passage of one of said cannulae out of said outer cannula.
 6. Theneedle assembly of claim 1, also comprising a manifold cannula intowhich said needle cannulae are manifolded.